Mount Prospect, Illinois 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

518
FXUS63 KLOT 031755
AFDLOT

Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
1155 AM CST Tue Feb 3 2026

.KEY MESSAGES...

- Lake effect snow showers will meander across the northeastern
  Illinois and northwestern Indiana shores of Lake Michgian
  Tuesday night into Wednesday morning, though accumulations
  should stay below an inch.

- Temperatures will make a run for the freezing mark toward the
  end of the week, marking the end of a prolonged stretch of
  daily highs below 32 degrees.

- A pattern change toward warmer temperature (highs and lows
  both above freezing) may materialize by the middle of next
  week.

&&

.DISCUSSION...
Issued at 211 CST Tue Feb 3 2026

Though Tonight:

Overnight water vapor imagery reveals an upper-level shortwave
moving into western Iowa early this morning, ahead of a
secondary shortwave and surface cold front dropping southward
through the Great Lakes. Ahead of both features, radar imagery
continues to depict a narrow band of snow slicing across eastern
Iowa and northern Illinois. Dry low-level air beneath the snow
band is relegating much of the returns to virga (we`ve only had
a few flurries at our office in Romeoville). However, very steep
lapse rates nearing 8 K/km in the DGZ (re: 00Z DVN RAOB) are
supporting convective elements within the band of snow, leading
to occasional radar reflectivity flaring to as high as 35 dBZ
and an impressively narrow region (only 5 to 10 miles wide) of
accumulating snow within the heart of the band.

Going forward, the snow band will continue moving across
portions of LaSalle, Grundy, southern Will, Kankakee, Newton,
and Jasper counties, including across portions of Interstates
39, 55, 57, and 80. Conditions will vary across short distances
in the aforementioned counties, going from completely dry to 1
inch per hour snow rates across literally a mile or two. Dry air
will still be problematic in the snow band, though currently
expect total snow accumulations to range from 1 to locally 4
inches, again within an exceptionally narrow 5 to 10 mile wide
region. Did put strong consideration into issuing a short fused
Winter Weather Advisory early this morning, but felt impacts
would be minimized due to relatively sparse travel volumes. With
that said, have issued a strongly worded Special Weather
Statement where conditions are expected to be worst this
morning. After daybreak, the band of snow may begin to weaken
(or just become more cellular rather than solid) as the lapse
rate plume is exhausted while dropping into potions of
Livingston, Ford, Iroquois, and Benton counties.

Just have to note... If we weren`t dealing with dry low-level
air problems this morning, the axis of 1 to 4 inches of snow
probably would have been more like 6 to 12 inches (if not more) of
snow. These narrow convective snow band events are the
wintertime equivalent of summertime training thunderstorm
events, and can just hammer the same area all day/night leading
to very pronounced impacts. So, thank you dry air.

Attention then turns toward the aforementioned cold front
dropping southward through the Great Lakes, which is due to move
through our area after daybreak. Lake effect parameters behind
the front look meager at best (inversion heights struggling to
climb past 4kft), though do suspect flurries may develop along
the southern shore of Lake Michigan as early as mid-morning.
Low-level convergence will gradually increase after sunset
tonight as a land breeze develops off of Lower Michigan, which
should allow for coverage of lake effect snow showers to
similarly gradually increase. Based on the expected orientation
of the low-level pressure field (surface high to our northwest
and surface low across the Ohio River Valley), steering flow
will acquire an easterly component overnight thereby guiding
lake effect snow showers toward northeastern Illinois. With all
of that said, the overall marine boundary flow looks weak maybe
10 to 15 kt), and the thermodynamics will remain marginal
(inversion heights struggling to climb past 5kft). So, lake
effect snow shower intensity should be fairly modest with the
highest coverage of showers struggling to move inland. In all,
this looks like a non-event with perhaps a dusting to locally
one half of an inch of snow generally from Chicago to Ogden
Dunes.

Elsewhere across the area, today look quiet. In spite of
clearing skies away from Lake Michigan, cold air advection will
hold temperatures to the upper 20s today. Light northerly winds
tonight with continued clearing skies away from the lake will
support overnight lows in the single digits near the Wisconsin
State Line to lower teens near the Indiana border.


Wednesday through the end of the week:

On Wednesday, a surface pressure ridge will slide through the
region leading to quiescent conditions. Lake effect stratus near
the IL/IN border should begin to finally eroding as inversion
heights crash toward the ground, giving way to partly sunny
skies across much of the area. The last vestiges of weak
northerly cold air advection will maintain highs similar to
Tuesday and in the mid to upper 20s.

Thursday into Friday, a pair of clipper systems will dive
southward from central Canada and into the Great Lakes. The
first wave on Thursday looks moisture-starved, though forecast
soundings look pretty darn close to supporting a period of
dry/fluffy snow, if not just flurries, from late morning to
early afternoon. The follow-up wave arriving overnight into
Friday morning will be the stronger of the pair, and will
support a period of snow showers focused near the Lake Michigan
shoreline. Aggressive warm air advection ahead of the wave may
push low-level thermal profiles precariously close to supporting
freezing rain as the precipitation type instead of snow, though
overall moisture looks limited suggesting total precipitation
amounts should be low (<0.05"). Temperatures will make a run
for the freezing mark on Thursday, and perhaps into the mid 30s
on Friday.

The push of cold air will lag the pair of shortwaves and arrive
this weekend, though the coldest air should push moreso into
Michigan and southern Ontario than our area. Highs this weekend
will nevertheless fall back toward the upper 20s to lower 30s.


Next Week:

Ensemble model guidance continues to exhibit a strong signal
that the stagnant upper-level northwesterly flow pattern across
the central US will finally break and become replaced by broad
upper-level southwesterly flow. As a result, ensemble mean
temperatures trend notably upward by the middle of next week and
beyond, with both high and lows well above the freezing mark.
In addition, the door will open for southwest flow synoptic
cyclones to lift toward the central US by next week, especially
in the February 11-14 timeframe.

Borchardt

&&

.AVIATION /18Z TAFS THROUGH 00Z THURSDAY/...
Issued at 1155 AM CST Tue Feb 3 2026

Aviation forecast concerns for 18Z TAFs:

- MVFR lake-induced stratocu for ORD/MDW/GYY develops this
  afternoon and persists into Wednesday.

- Period of lake-effect snow showers mainly for MDW/GYY tonight
  into Wednesday morning. IFR vis possible at times along with
  some minor accums.

A subtle trough pushing south across Lake Michigan at midday
will shift winds at ORD/MDW/GYY to NNE/NE shortly. This will
also spread lake-induced MVFR stratocu into these terminals
early this afternoon. Forecast soundings indicate this stratocu
layer is fairly shallow, and warmer than more favorable snow
crystal generation temps. Thus while can`t completely rule out a
few non-impactful flurries, do not think they`ll be significant
enough for TAF inclusion this afternoon except perhaps at GYY.

High-res models continue to indicate deepening cloud depth and
colder temps aloft and a more substantial snow shower potential
later this evening into early Wednesday morning, with guidance
primarily highlighting the MDW-GYY terminals. Periods of IFR
vis and some light accums (1" or less) are possible for these
locations. At this time, ORD looks to be just northwest of the
better snow shower coverage, though current probabilities (20%)
are below mentionable TAF criteria. Will have to monitor
position of the band later tonight in case this needs to be
included for ORD, which would likely be in the 07Z-13Z time
range if it occurred.

Otherwise, winds are expected to turn back to NNW later this
evening into Wednesday. Farther away from the lake, VFR
conditions are expected to prevail at DPA and RFD.

Ratzer

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...None.
IN...None.
LM...None.

&&

$$

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